CCC 1499 "By the sacred anointing of the sick and the prayer of the priests the whole Church commends those who are ill to the suffering and glorified Lord, that he may raise them up and save them. and indeed she exhorts them to contribute to the good of the People of God by freely uniting themselves to the Passion and death of Christ."
1500 Illness and suffering have always been among the gravest problems confronted in human life. In illness, man experiences his powerlessness, his limitations, and his finitude. Every illness can make us glimpse death.
1501 Illness can lead to anguish, self-absorption, sometimes even despair and revolt against God. It can also make a person more mature, helping him discern in his life what is not essential so that he can turn toward that which is. Very often illness provokes a search for God and a return to him.
1502 The man of the Old Testament lives his sickness in the presence of God. It is before God that he laments his illness, and it is of God, Master of life and death, that he implores healing. Illness becomes a way to conversion; God's forgiveness initiates the healing. It is the experience of Israel that illness is mysteriously linked to sin and evil, and that faithfulness to God according to his law restores life: "For I am the Lord, your healer." The prophet intuits that suffering can also have a redemptive meaning for the sins of others. Finally Isaiah announces that God will usher in a time for Zion when he will pardon every offense and heal every illness.
Christ the physician
1503 Christ's compassion toward the sick and his many healings of every kind of infirmity are a resplendent sign that "God has visited his people" and that the Kingdom of God is close at hand. Jesus has the power not only to heal, but also to forgive sins; he has come to heal the whole man, soul and body; he is the physician the sick have need of. His compassion toward all who suffer goes so far that he identifies himself with them: "I was sick and you visited me." His preferential love for the sick has not ceased through the centuries to draw the very special attention of Christians toward all those who suffer in body and soul. It is the source of tireless efforts to comfort them.
1504 Often Jesus asks the sick to believe. He makes use of signs to heal: spittle and the laying on of hands, mud and washing. The sick try to touch him, "for power came forth from him and healed them all." and so in the sacraments Christ continues to "touch" us in order to heal us.